ISIS moves to develop chemical weapons, Carter says

U.S. Defense Secretary Ash Carter and lawmakers expressed concern that Islamic State is moving to develop chemical weapons even as the U.S.-led coalition makes progress against the terrorist group in Iraq.

The coalition is "going after ISIL's attempts to develop chemical weapons, as we continue to ensure that U.S., coalition and Iraqi troops are vigilantly protected from that threat," Carter said Thursday at a Senate Armed Services Committee hearing, using an acronym for the terrorist group.

In one of the "single largest airstrikes" of the campaign against ISIS, Carter said, warplanes last week destroyed a pharmaceutical facility near Mosul, Iraq, that the group planned to use to make chemical weapons. Pentagon officials have said the plant was intended to produce chlorine gas.

On Tuesday, a rocket that may have carried a chemical agent landed near the security perimeter at the Qayyarah airbase in Iraq, where hundreds of U.S. personnel are stationed to support the planned Iraqi assault to retake Mosul. Tests on the rocket were continuing.

"We assess it to be a sulfur mustard blister agent," Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said at the hearing. "It went on one of our bases," where there's effective detection and protection equipment as well as decontamination capabilities, according to the general. He said the coalition has carried out 30 strikes over the past year targeting Islamic State's "emerging chemical capability."

A top Iraqi general said ISIS, another acronym, has tried to use "expired" chemical weapons against his nation's troops before with "no real impact on our forces."

"They are desperate and collapsing and try to use these attacks for psychological reasons only," said Gen. Najim Abdullah al-Jabouri, who is leading the campaign to retake Mosul.